Hormone levels in adult males can taint the taste of the meat. Females or younger ales are best. Older males should be cut few weeks before slaughter, which isn't easily done to wild hogs. Some opinion here.

They aren't that easy to sex. Last year a local hunting preserve gave me a deal on a older "female" that wasn't breeding that turned out to be a castrated male. They forgot more about hogs than I know and got it wrong. Some pics on pages 10-11 of this pdf give you a clue what to look for.